From the Guidelines
Laboratory tests for PCOS should include LH, FSH, prolactin, progesterone, testosterone, androstenedione, DHEAS, glucose, and insulin levels, as well as pelvic ultrasound, to confirm diagnosis and evaluate metabolic health. When evaluating women with suspected PCOS, it is essential to consider the hormonal and metabolic abnormalities associated with the condition 1. The diagnosis of PCOS is based on the presence of hyperandrogenic chronic anovulation, which can be indicated by low mid-luteal phase progesterone levels and hypersecretion of luteinising hormone 1.
Key Laboratory Tests
- LH and FSH levels to evaluate the LH/FSH ratio, which is often elevated in women with PCOS 1
- Prolactin levels to rule out hyperprolactinemia, which can also cause menstrual irregularities 1
- Progesterone levels to confirm ovulation, with low levels indicating anovulation 1
- Testosterone and androstenedione levels to evaluate hyperandrogenism, with elevated levels suggesting PCOS or other androgen excess disorders 1
- DHEAS levels to rule out non-classical congenital adrenal hyperplasia, which can also cause hyperandrogenism 1
- Glucose and insulin levels to evaluate insulin resistance and metabolic health, with elevated glucose/insulin ratio suggesting reduced insulin sensitivity 1
Additional Evaluations
- Pelvic ultrasound to visualize ovarian morphology and detect polycystic ovaries, which are often associated with PCOS 1
- Transvaginal ultrasound, while not a lab test, is important to confirm the presence of polycystic ovaries and evaluate ovarian morphology 1
These tests should be performed during the follicular phase (days 3-5 of menstrual cycle) when possible for accurate hormone assessment 1. The results of these tests will guide treatment approaches, which may include lifestyle modifications, metformin for insulin resistance, or hormonal contraceptives for menstrual regulation and androgen suppression.
From the Research
PCOS Lab Tests
The following lab tests are commonly used to diagnose and monitor Polycystic Ovary Syndrome (PCOS):
- Fasting plasma glucose test
- Oral glucose tolerance test (OGTT)
- Insulin and glycosylated hemoglobin (HbA1c) levels
- Fasting lipid profile
- Luteinizing hormone (LH) and follicle stimulating hormone (FSH) measurements
- Total testosterone, derived free testosterone, sex hormone binding globulin, androstenedione, and dehydroepiandrosterone (DHEA) measurements
Recommended Screening Tests
According to the American College of Obstetricians and Gynecologists and the Endocrine Society, all women with PCOS should undergo screening for impaired glucose tolerance and dyslipidemia with a 2-hour 75g OGTT and fasting lipid profile upon diagnosis, and repeat screening every 2-5 years and every 2 years, respectively 2. The 2-hour OGTT is preferred over HbA1c as a superior indicator of impaired glucose tolerance/diabetes mellitus in women with PCOS 2, 3.
Diagnostic Agreement between FPG and OGTT
A study found that relying only on fasting plasma glucose (FPG) missed as many as 40% of women with dysglycemia, including all cases of diabetes, and that the diagnostic agreement between FPG and OGTT was only 0.55 4. The areas under the receiver operating characteristic curve for dysglycemia were 0.86 for FPG and 0.91 for 120-min plasma glucose during the OGTT, indicating that OGTT is a more accurate test for diagnosing disorders of glucose tolerance in women with PCOS 4.
Hormonal Markers
A study found that total testosterone was the most frequently abnormal biochemical marker for PCOS, and that the combination of testosterone, androstenedione, or LH, either alone or in combination, were raised in 86% of women with PCOS 5. The study also found that the LH/FSH ratio was not a sensitive marker for PCOS and should be abandoned as a biochemical criterion for diagnosis 5.